Explanation
In this vocabulary item, Reduce is the closest synonym of Curtail, so option D is correct. The word Curtail and the word Reduce share the same central sense in the context tested by the question, although usage, tone and grammatical form should still be checked before substituting one for the other. A synonym is not required to be identical in every possible sentence; it must preserve the intended meaning in the relevant context. Here, replacing Curtail with Reduce keeps the core idea intact without reversing the tone or changing the action, quality or state expressed by the target word. The alternatives Distinguished, Beg and Summon do not express the same central meaning as Curtail. This distinction matters because competitive examinations often place one accurate synonym beside three familiar but contextually unsuitable words. To verify Curtail independently, identify its part of speech, state a short definition, and place both Curtail and Reduce in the same simple sentence. If the sentence retains its essential meaning and grammatical structure, the synonym relationship is supported. Learners should revise Curtail together with Reduce, a brief usage cue and the contrasting distractors.